The present invention relates to methods for enhancing well productivity and minimizing water production using swellable polymers.
Various methods are known for fracturing a subterranean formation to enhance the production of fluids. In a hydraulic fracturing operation, a pressurized fracturing fluid can be used to hydraulically create and propagate a fracture within the subterranean formation. Fracturing fluids can also carry and deposit solids such as proppants into the fracture. Inside the fracture, the proppants can form a tightly packed permeable mass (sometimes referred to as a “proppant pack”). The proppant pack serves as a physical barrier that prevents the fracture from fully closing and as a conduit through which production fluids can flow. The degree of success of a fracturing operation depends, at least in part, upon the fracture conductivity once the fracturing operation is stopped, the hydraulic pressure is removed, and production is begun. The conductivity of these proppant packs may be limited because of the relatively small interconnected interstitial spaces between the packed proppant.
A fracturing approach that involves placing a much reduced volume of proppants in a fracture has been used to increase the size of the interconnected interstitial spaces in proppant packs. In such operations, the proppant particulates within the fracture may be widely spaced but still sufficient to hold the fracture open and allow for production fluids to flow. An increased fracture conductivity may result due to the fact that the produced fluids may flow around widely spaced proppant rather than through the relatively small interstitial spaces within a proppant pack. While this fracturing concept has been investigated in the industry, its widespread usefulness is still somewhat limited for a number of reasons. Among other things, settling of proppant can be particularly problematic when fracturing with a reduced volume of proppants. Proppant settling may lead to a fracture or a top portion of a fracture closing, which can lower the conductivity of the propped fracture and result in proppant aggregation, rather than discrete proppant pillars, thereby defeating any added benefit of the widely spaced proppant. Water encroachment depends on the location of the water zone with respect to the oil producing interval and the rate at which oil is produced. Generally, the closer a water zone is to an oil producing interval and the higher the rate of oil production, the more likely water encroachment will occur. The resulting water production may lead to a number of issues including poor hydrocarbon recovery efficiencies, completion inefficiencies, and well maintenance problems including, but not limited to, sand production, sand separation, sand disposal, water separation, or water disposal. Therefore, a method of preparing widely spaced proppant in proppant packs that are not susceptible to partial or complete fracture closure and that are capable of reducing or minimizing water encroachment during fracturing and production operations may be of benefit to one of ordinary skill in the art.